Re: Newbie first questions
>So the core of my worry is basically, 'Surely you can't just boot off the dist >ribution media, get a barebones TTY window and then Amanda will restore >everything with an under-the-covers tar -xvf rmt0 /' It depends on the OS, but you're right, there is usually some other work you will have to do before turning Amanda loose on the bulk of the data. >There are two problems, right away >1) I guess you have to reconstruct the partitions first (in Linux too?) If you're starting from a brand new disk, then yes. >2) What do you do about boot records, hidden system files ... You figure out what you need to do ahead of time (as I said, installboot for Solaris, and Bernhard gave the basics for Linux) and write it down on paper in your procedures book. :-) Some OS's (I think Linux falls in this category) have packages that let you create a boot-able medium that can do a lot of this for you, ala mksysb. But that's a Linux question, not an Amanda one (although there is probably plenty of expertise on this list). FYI, there has been some discussion in the past about adding special files to the Amanda tapes to help with disaster recovery. For instance, it could be a tar of various config files to make putting things back together easier. Or it could be a script that actually did the work (writing the script would be an exercise left to you :-). >... and sparsely-written > data (you *don't* restore Oracle from a tar tape, fr'instance)... Now you've gone "below" Amanda. Amanda is a manager of other backup programs. It does not actually do backups itself (it doesn't read the disk, etc). However, all dump style programs (backup, ufsdump, dump, etc) handle sparse files. What comes back will be what was there to start with. GNU tar can also do sparse files, and Amanda runs it with the flags needed to do so. Databases (e.g. Oracle), though, are another matter. Those are not just sparse files. They are also "live" and you can't just back them up while the engine is running. There are numerous ways around this (check the mailing list archives). We run Oracle here and do it by having a large "backup" area that we tell Oracle to write its own backups into, then we use Amanda to dump that. See: ftp://gandalf.cc.purdue.edu/pub/amanda/dbbackup.* It's a little out of date, but should still work. And yes, I've even had to restore from them. >... and these will be different with each OS >and then there are possible other concerns.. Yup. In general, you need to know what you're doing. That's why us backup folks rake in the huge bucks :-). >3) You have booted (off the installation media, I guess) and are running syste >m code...what happens when you overwrite code you're running. ... Ummm, if you booted off installation media, such as a CD-ROM, you *can't* overwrite the code being run :-). It's called "Read-Only" for a reason. Taking Solaris as an example, I would boot off the CD and at that point (well, after answering a lot of annoying questions), I'd have a normal TTY window, but it's all associated with the CD. Next I'd re-partition the disk drive (if needed), newfs the partitions, and finally mount and restore into them. FYI, I've done this lots of times. I don't even bother waking up any more :-). Note that you don't need Amanda laying around to do this. Amanda tape images can be processed with normal Unix tools (mt, dd and whatever restore program matches the dump format). The one thing you might want to be careful about is compression. Just to be safe, I would probably *never* software compress my OS file systems on the off chance I didn't have the uncompress program during such a disaster recovery. >S. John R. Jackson, Technical Software Specialist, [EMAIL PROTECTED]
Re: Newbie first questions
THANK YOU all for your thoughtful replies. So often when I ask questions, I end up with the dissonance of dueling paradigms...like a telepathic blind person talking with someone with a 'normal' sensorium. My experience on restoring machines has been with Microsoft, which doesn't rebuild very cleanly at all, and IBM's AIX which does it magically well, particularly with Sysback (which costs money, but is supported under the AIX service contract once you've purchased it). So the core of my worry is basically, 'Surely you can't just boot off the distribution media, get a barebones TTY window and then Amanda will restore everything with an under-the-covers tar -xvf rmt0 /' There are two problems, right away 1) I guess you have to reconstruct the partitions first (in Linux too?) 2) What do you do about boot records, hidden system files and sparsely-written data (you *don't* restore Oracle from a tar tape, fr'instance)and these will be different with each OS and then there are possible other concerns.. 3) You have booted (off the installation media, I guess) and are running system code...what happens when you overwrite code you're running. I know that, if I'm running a script in a normal environment AND I update and save that script during its run, funny and weird things happen. Wouldn't that be the case with OS system code as well? In all honesty, this is not so much an Amanda question (though anyone using A. must deal with it to do a system restore) as it is a OS-peculiarities question. Unfortunately, someone has absconded with my O'Reilly 'Unix Backup and Recovery Book', which should answer some of those questions. Does anyone suggestions for other books on the same topic (the problems #2 & #3) or have a good chapter on it for Solairs and LInux? I have the Running Linux book but it only talks about file restoration, not system restoration. There are all sorts of magical possibilities inherent in a Logical Volume Manager...which IBM has and gave to Linux...I am waiting/hoping for a Linux mksysb equivalent. FWIW, Sysback will work with mulitple tapes and supports tape streamingif any AIXers would like more info on Sysback, feel free to drop me a line. Again thanks for thoughtful help! S. -- Stewart Dean, Unix System Admin, Henderson Computer Resources Center of Bard College, Annandale-on-Hudson, New York 12504 [EMAIL PROTECTED] voice: 845-758-7475, fax: 845-758-7035
Re: Newbie first questions
> You do get into issues where there is more than the file system involved. > In AIX, that would be the dreaded ODM :-). Even in Solaris, you would > need to run installboot to write the boot sector. I don't know enough > about Linux, but I wouldn't be surprised to find out there's more than > just a dump of "/" involved there, too. Basically you restore the / filesystem, do "chroot . sbin/lilo" in it and you are ready to run.
Re: Newbie first questions
> I read Amanda doc and I read about backup but it doesn't fit with my understanding. >I can see dumping (ufsdump on Solaris) a whole filesystem and > restoring itthough how you get an individual file out of it, is another thing. >I can see taring a filesystem so that you can give the idiot user > back his deleted filesthough how you would use a tar'ed tape to restore an OS is >another thing. It's sort of like building a bridge while > standing on thin air...maybe Wile Coyote can do it (for a while, until he looks >down). How do you do both? AIX and sysback have built-in magic, > but. Here's what I do with AIX: do once in a month an mksysb tape and daily Amanda runs. mksysb only backups the rootvg! This is for a bootable tape in case the drives fail. Every filesystem in each VG is backed up by Amanda. No experience yet with sysback.
Re: Newbie first questions
>I ask you patience, understanding and help. ... That's pretty much the motto of this mailing list :-). >First let me explain my paradigm, so you'll understand my questions. ... That was well described. First, we run quite a bit of AIX here, as well as Solaris and a bit of Linux. So our situations are similar. Basically, you have things right. Amanda is not a disaster recovery backup in the sense of pop the tape in, boot from it and when you come back the system is up and running. It is more of a file system and individual file recovery tool. If the system completely croaks, Amanda expects you to get it booted in some way (for Solaris, that's probably from an installation CD), then you can use Amanda to get your data back. FYI, we do both Amanda and mksysb's on our AIX systems (and I do what I call a "root-emergency" tar of my Solaris systems). There is way too much data for mksysb, so those tapes are only to get a system back on its feet after a complete mess. After that, Amanda would be used to bring back the homes, optional stuff, etc. >... I can see dumping (ufsdump on Solaris) a whole filesystem and >restoring itthough how you get an individual file out of it, is >another thing. ... The flip side of ufsdump, ufsrestore, allows individual files to be selected for restoration. In fact, any restore program I know of (including tar) does. So to pull back just a few files for a user is just a matter of knowing what command line flags to use. One of the things Amanda provides is a common interface. So, for instance, you tell Amanda you want a particular file back, and it deals with whether the image was created with backup, dump, ufsdump, tar or whatever. >though how you would use a tar'ed tape to restore an > OS is another thing. ... Tar is capable of dumping everything in a file system. If everything your OS needs to run is in the file system, a tar restore (once the machine is booted, e.g. from CD) works fine. You do get into issues where there is more than the file system involved. In AIX, that would be the dreaded ODM :-). Even in Solaris, you would need to run installboot to write the boot sector. I don't know enough about Linux, but I wouldn't be surprised to find out there's more than just a dump of "/" involved there, too. These items are outside the realm of Amanda. We assume you're proficient enough with your OS to deal with them. You're also right that keeping other information (partitioning for instance) is important for non-AIX systems. However, that's true regardless of whether Amanda is involved or not. So, does that explain things a bit? If you have other questions, just post. >Stewart Dean John R. Jackson, Technical Software Specialist, [EMAIL PROTECTED]
Newbie first questions
I am interested in Amanda, but my vision of backup/restore is colored by my previous experience with them...so much I what I've read (the Unix Backup chapter, etc) is dissonant with my own conceptual backup paradigm. I ask you patience, understanding and help. First let me explain my paradigm, so you'll understand my questions. I come from an AIX background, from mksysb or its more powerful descendant, sysback. mksysb is a fire and forget full system backup and restore. One command get you the operating system complete. The machine fails, you stuff in the tape, start the machine, and, when the tape finishes, everything is back...you do get some choices, but basically the OS and data included with it gets restored without your fiddling with partitions or original OS media or patches: Backup to one tape, restore from one tape, virtually no sysadmin interaction. Magic. Sysback does the same with more bells and whistles...incremental backups, restore to different IBM processor platform, backup/restore of non-OS data filesystems, restore of individual files up to the whole OS. More Magic. So: I can restore individual user files (nothing you couldn't do with tar) or reincarnate a fire/flood destroyed server onto new hdwe with the same tape. But now I have Sun and Linux machines to backup as well. I read Amanda doc and I read about backup but it doesn't fit with my understanding. I can see dumping (ufsdump on Solaris) a whole filesystem and restoring itthough how you get an individual file out of it, is another thing. I can see taring a filesystem so that you can give the idiot user back his deleted filesthough how you would use a tar'ed tape to restore an OS is another thing. It's sort of like building a bridge while standing on thin air...maybe Wile Coyote can do it (for a while, until he looks down). How do you do both? AIX and sysback have built-in magic, but. OK, I know that most OSes haven't got the stuff to automagically restore themselves like AIX...anyway, to restore a Solaris machine, you ufsdump all filesystems, then, to restore, you have to install from the media, partition the disk(s) (you did save the partition info, right?) and then ufsrestore the filesystems one at a time. After AIX stuff, this is incredibly clanky, labor intensive and error prone, but hey Sun is an industry leader. But at least this makes some sense to me. Doing it from a tar doesn't seem possible. Enlighten my darkness...or is Amanda not a disaster recovery backup, but only individual file backup/restore system? -- Stewart Dean, Unix System Admin, Henderson Computer Resources Center of Bard College, Annandale-on-Hudson, New York 12504 [EMAIL PROTECTED] voice: 845-758-7475, fax: 845-758-7035
